Page 98 - Build 165

Departments/LBP knowledge By Paul Hobbs, Registrar Building Practitioner Licensing
Timber-framing and foundations
Holes and notches, and setting out foundations have been causing issues for some builders. Let’s revisit some common problems.
TWO ASPECTS of timber-framed building work that are common in complaints about LBPs to the Building Practitioners Board and enquiries to MBIE’s technical team are: ● holesandnotchestostudsandjoists
● foundationset-out.
Handy reference guide to NZS 3604:2011
NZS 3604:2011 Timber-framed buildings is a core means of compliance for light timber- framed building work. A helpful reference guide containing selected extracts from the standard is also available – SNZ HB 3604:2011 Timber-framed buildings — Selected extracts from NZS 3604:2011.
This provides users with figures and tables extracted from NZS 3604:2011 commonly used on site or in the design office. It is useful for those without ready access to the full version of the Standard. Easy to get standard and handbook
NZS 3604:2011 can be purchased on the Standards New Zealand website. MBIE has sponsored the handbook SNZ HB 3604:2011 and it is free to download from the Standards New Zealand website.
Holes and notches to studs and joists
Some common methods of construction have changed or been modified to help achieve
greater levels of energy e ciency in our homes. An example is the move from 90 × 45 mm to 140 × 45 mm timber wall framing to provide enough depth for thicker wall insulation.
NZS 3604:2011 and the handbook provide notching and drilling limits for 90 mm deep wall framing but not for 140 mm deep wall framing: ● For 90 mm framing, the maximum size limit
of the hole or notch is no more than 25 mm
– 27% of the width of the stud (see Figure 1). ● For 140 mm framing, the maximum size of a hole or notch would be 38 mm (27% of 140 mm), although this is not covered by NZS 3604:2011. The 140 mm wall depth o ers additional opportunities for the size and position of services plumbers and electri- cians can run through holes in the framing. References to checking and boring studs are in section 1.5.3 of the handbook and in
section 8.5.1.6 of NZS 3604:2011.
To drill bigger holes in studs or oor joists, refer to the NZS 3604:2011 full text. Alterna- tively, use one of the proprietary supports available on the market that allow a larger diameter hole to be drilled. Drill in the centre of the stud and follow the spacing requirements.
Foundation set-out
Several Building Practitioners Board complaints have considered issues about
45 mm
hole
notch
90/140 mm
25/38 mm diameter
25/38 mm
200 mm maximum
96 — April/May 2018 — Build 165
Figure 1: The maximum diameter of holes and depth of notches is 25 mm in 90 mm studs and 38 mm in 140 mm studs.
foundation set-out, siting or accuracy of layout of a house slab. The most common area of concern for foundation-related complaints is where the foundation set-out is found to be inconsistent with the consented drawings. Move to foundation specialists
Modern methods of construction often involve foundation specialists laying the foundations